gluconeogenesis and glycolysis and CAC

What is the main purpose of gluconeogenesis?

To make glucose from non-carbohydrate sources.

Where does gluconeogenesis occur?

Mainly in the liver, also in the kidney cortex.

What are the main carbon sources for gluconeogenesis?

Lactate, glycerol, and alanine.

Where in the cell does gluconeogenesis occur?

Mitochondria, cytosol, and ER for the final step.

What provides the energy for gluconeogenesis?

Fatty acid oxidation.

How many ATP and GTP are used per glucose in gluconeogenesis?

4 ATP, 2 GTP, and 2 NADH.

What enzyme converts pyruvate to oxaloacetate?

Pyruvate carboxylase.

What activates pyruvate carboxylase?

Acetyl-CoA.

What enzyme converts oxaloacetate to PEP?

Phosphoenolpyruvate carboxykinase (PEPCK).

What enzyme converts fructose-1,6-bisphosphate to fructose-6-phosphate?

Fructose-1,6-bisphosphatase.

What enzyme converts glucose-6-phosphate to glucose?

Glucose-6-phosphatase.

What activates glycolysis?

AMP and fructose-2,6-bisphosphate.

What inhibits glycolysis?

ATP, citrate, and low pH.

What activates gluconeogenesis?

ATP and citrate.

What inhibits gluconeogenesis?

AMP and fructose-2,6-bisphosphate.

What hormone promotes glycolysis?

Insulin.

What hormone promotes gluconeogenesis?

Glucagon.

What is the function of the pyruvate dehydrogenase complex?

Converts pyruvate into acetyl-CoA.

Why is PDH a crucial metabolic juncture?

It commits carbon to the TCA cycle and cannot be reversed to glucose.

Which enzyme in PDH uses TPP?

E1: Pyruvate dehydrogenase.

Which enzyme in PDH uses lipoamide?

E2: Dihydrolipoyl transacetylase.

Which enzyme in PDH uses FAD and NAD+?

E3: Dihydrolipoyl dehydrogenase.

What activates PDH?

ADP, NAD+, CoA, and Ca2+.

What inhibits PDH?

ATP, NADH, and acetyl-CoA.

PDH inactivation

PDH kinase phosphorylates E1.

PDH activation

PDH phosphatase dephosphorylates E1.

Primary purpose of the citric acid cycle

To oxidize acetyl-CoA and produce NADH, FADH2, and GTP.

Location of the citric acid cycle

In the mitochondrial matrix.

NADH and FADH2 production per acetyl-CoA

3 NADH, 1 FADH2, and 1 GTP.

First enzyme of the TCA cycle

Citrate synthase.

Enzyme converting citrate to isocitrate

Aconitase.

Enzyme converting isocitrate to alpha-ketoglutarate

Isocitrate dehydrogenase; produces NADH and CO2.

Enzyme converting alpha-ketoglutarate to succinyl-CoA

Alpha-ketoglutarate dehydrogenase; produces NADH and CO2.

Enzyme converting succinyl-CoA to succinate

Succinyl-CoA synthetase; produces GTP.

Enzyme converting succinate to fumarate

Succinate dehydrogenase; produces FADH2.

Enzyme converting fumarate to malate

Fumarase.

Enzyme converting malate to oxaloacetate

Malate dehydrogenase; produces NADH.

Activators of isocitrate dehydrogenase

ADP and Ca2+.

Inhibitors of isocitrate dehydrogenase

ATP and NADH.

Inhibitors of alpha-ketoglutarate dehydrogenase

Succinyl-CoA and NADH.

Activator of alpha-ketoglutarate dehydrogenase

Ca2+.

Inhibitors of citrate synthase

ATP, NADH, and citrate.

TCA cycle amphibolic nature

It functions in both catabolism and anabolism.

Amino acid derived from alpha-ketoglutarate

Glutamate.

Amino acid derived from oxaloacetate

Aspartate.

Compound from TCA used to make heme

Succinyl-CoA.

Compound from TCA used to make fatty acids

Citrate (exported to cytosol).

Enzyme replenishing oxaloacetate from pyruvate

Pyruvate carboxylase (anaplerotic reaction).